Combustion regulation



Oct. 16, 1934. c; TEMPLE 1,977,024

COMBUSTION REGULATION Filed July 5, 1952 2 Sheets-Sheet 1 INVENTOR P4 UL C. TEMPLE BY Q54; f

ATTORNEY Oct. 16, 1934. P. C. TEMPLE COMBUSTION REGULATION 2 Sheets-Sheet Filed July 5, 1952 REGULATOR Pos/ r/o/v INVENTOR P4 UL C. TEMPLE 1;, ATTORNEY \SQ m km Ev Patented Oct. 16, 1934 tartan rarer COMBUSTION REGULATION Paul 0. Temple, Decatur, 111., assignor to A. W.

Cash Compan ,Delaware y, Decatur,-Ill., acorporation of Application July. 5, 1932,} Serial No. 620,839

8 Claims.

This invention relates to combustion regulation, and-more particularly to theautomatic regulation of the combustion of finely divided fuels, such as pulverized: coal, whichare burned-in suspension -in-a furnace chamber.

When fuel-is burned in this manner in a large furnace, it is customary to provide'a. plurality oi burners for the introduction of the "fuel'into the furnace. It is also customarytovary the number ofburners in operation whenever the load onthe furnace chan'gesito'any considerableextent. For example,-'a furnace'mayhave four burners, all-of which will be-inuse whenthedemand for heat is high; whereas one burner alone may suiiice to carrythe load whenithe demand for heat is low. Four burners will require four. times as much air as one burner-for: a giveni-rate of. fuel feed per burner. Hence-thecorrect rate of air supply to the furnace, at boththeminimum and the maxi-- mum loads-,. will depend uponthe numberv of burnersinwservice. A diflicult'problem is presented :incontrolling the combustion automatically in a furnace installationof this type.

Itis accordingly one object of-the inventionito provide an automatic regulating-system for a furnace having aplurality of burners, whichmay be readily adjusted to provide the correct. supply of air-in accordance withthenumber. of burners in operation. I It is a further object of the inventiontorprovide a controldevice, such as a damper, to regulate the rateof air flow to aplurality, of burners,.and connecting meansbetweenthe control device and an automatic regulator, the connectingmeans being adjustable to vary the position of thecontrol device with respect to the regulator in accordance withthe number of burners in service.

It is a further object of the invention to provide a simple and easily adjustable. mechanism for connecting an automatic regulator. to a movable control device, which is so arranged that the total movement of the control device and its initial position may be varied as desired.

With these and other objects inview, as will be apparent to those skilled in the art; the invention resides in the combination of parts set forth in the specification and covered pended hereto.

Referring to the drawingsillustrating one em-. "bodiment of the invention, and in which like ref- 'erence numerals indicatelike parts,

Fig. l is a somewhat diagrammatic-view showing a'combusti'on regulating system in* connec- I tion-witha' steam generating furnace; I

Fig; 2 is'a plan view of the adjusting mecha nism by the claims apused in the regulating system, certain parts being shownin section for clearness of illustration;

Fig. 3 is a sectional elevation of themechanisin shown inFig; 2;

Fig.4 is a kinematic diagram showing the relative movem nts of certain parts of the regulating system; and

Fig. 5 is a chart showing the rate of air flow re-- quired at dilferent regulator positions with difierent numbers of burners in operation.

The embodiment illustrated comprises a steam generating furnace 10 having a steam discharge .pipe 11- and provided with four pulverized fuel burners 12.- Each burner 12 is supplied with pulverized fuel-through a pipe 14 leading from a pu verizing apparatus 15, which is supplied with coarse fuel, such as coal, by means of a-feeding mechanism 16 drivenby a variable speed electric motor 18. Each motor '18 is connected by wires 19 to a'source of electric power 20 and to a rheo- F5 stat 22 which serves tocontrolthe speed of the motor and hence-the rate of fuel feed. A switch 23 is provided for each motor, whereby. the motor may berendered inoperative when desired. Each .pulverizer 1 5 is driven by a suitable source of S0 power, such as a motor or turbine (not shown).

The burners 12 are supplied with air through branch ducts 24 provided with manually operable dampers 26. A single duct 2'? provided with a main damper 28 connects all four ofthe branch duc'ts24ito arhain duct 29 which is supplied with air under pressure from a suitable source (not shown).

I In order to vary the rate of fuel feed automatically in accordance with the demand for heat, I provide asuitable automatic regulator 31 which is connected to the steam discharge pipe 11 by means of a pipe32. This regulator is preferably of the compensated type having a piston movable through afixed stroke in response to changes in 95. steam .pressure through a definite operating range,

and capable of maintaining intermediate positions without hunting. By way of example, the operating range in a particular installation might be from idfi'pounds steam pressure-at minimum demand to 450 pounds steam pressure at maximumdemand, and the'regulator may be so construoted that it will assume its lowest position at @60 pounds and its highest position at 450 pounds. The movements of the regulator are transmitted to the'rheostats 22,and for this purpose I have connected the lower ends of the rheostat arms 33 by means ofv a rod 35 which is actuated from the upper end of the regulator piston rod 36 by means 'ofa bell crank-3'7.

For simplicity of illustration I have shown the air control damper 28 operated by the regulator 31, but it will be clear that a separate regulator may be utilized if desired. The connections between the regulator and the damper comprise a bell crank 39 actuated from the lower end of regulator piston rod 36, and joined by a rod 40 to an arm 41 keyed to a shaft L3. This shaft 43 is rotatably supported in bearings carried by brackets 4.4 mounted on a vertical panel 45. An arm a? is keyed to the shaft 43 and this arm is joined by a rod 48 to a lever 49 pi votally supported on a pin 51. A rod 52 connects the lever 49 with the operating arm 53 of the damper 28. The various parts are so arranged that as the regulator moves upwardly in response to an increased demand for steam, the resistance of the rheostats 22 will be increased to speed up the feeder motors l8, and the damper 28 will be moved toward open position to increase the flow of air to the burners.

It will now be apparent that from one to four of the burners 12 may be in operation, depending upon the rate of steam generation desired. To remove a burner from service, it is merely necessary to open the proper switch 23, stop the pulverizer 15, and close the damper 26 in the branch duct 24 leading to the burner. So long as a given burner is operating, its damper .26 will be left wide open, the air flow being controlled by the damp r 28. It will be clear that the stroke of the regulator 31 and its operating range will remain the same regardless of the number of burners in service, but the air requirements corresponding to different regulator positions will vary widely. This is shown graphically in Fig. 5, which indicates that the retically four burners will require substantially four times as much air for each regulator position as one burner. In actual practice, such variables as air leakage into the furnace may slightly modify the theoretical requirements. In any event, it is apparent that damper 28 must be given different minimum positions and different total movements throughout the operatin range, in accordance with the num ber of burners operating.

In the embodiment illustrated, this is accomplished by varying the effective length of the arm 47, and the result of this change is shown diagrammatically in Fig. 4, in which A represents the position of the arm at the minimum load position of the regulator, and 3 represents the position of the arm at the maximum load position of the regulator. As the arm moves from A to B, with its effective length adjusted for four burner the lever 49 will move from C to D. The same movement of the arm, with its effective shortened to the correct value for one burner operation, will move the lever 49 from E to Since the damper 28 is operated directly from the lever l9, the damper will be given corresponding movements. Intermediate effective lengths for the arm 47 will result in the desired damper movements for two or three burner operation. It will be noted that the arm 47, even when in position A, makes an obtuse an le with the rod &8, so that shortening of the arm will not only reduce the total travel of the damper 28 but it will also decrease the damper opening corresponding to position A. Various other linkages may be utilized to produce the same result.

In order that the effective length of the arm i7 may be conveniently adjusted, I connect the upper end of the rod &8 to a nut 55 which is mounted on a screw-threaded shaft 56 rotatably supported in bearings 57 on the arm. This shaft 56 preferably adjustable in angularity on the arm, to enable the desired damper movements to be obtained more easily at installation. This is accomplished by providing the bearings 57 with studs 59 which project through slots 50 in the arm 47. Nuts 61 on the studs serve to clamp the parts firmly together. It will be apparent that if the shaft 56 is adjusted to a greater angle with the rod 48, a given change in effective length of the arm 47 will produce a greater change in the position of the damper 28. The rod 48 is preferably made adjustable in len th by means of a turnbuckle 63, and a series of holes as may be provided in the lever 49 for connection of the rod thereto at different points. It will be understood that except for the adjustable length of the arm l7, these Various adjustments are merely for convenience at installation, and after they have once been properly set they will not be changed in normal operation.

The shaft 56 is arranged to be rotated manually, preferably from a position in front of the panel 45. For this purpose I have'provided a bevel pinion 66 on the front end of the shaft which meshes with an idler bevel gear 67 rotatably supported on a stud 68. This stud is parallel with the shaft 43 and is supported by a bracket 70 (Fig. 2) extending forwardly from the front bearing 57. A rotatable shaft 71 extends through a slot 72 in the panel 45, and care ries a handwheel 74 on its front end and a bevel pinion '75 on its rear end. The pinion 75 meshes with the idler gear 67. The forward portion of the shaft 71 is slidably and rotatably supported in a sleeve 76 which is pivotally fastened to a bracket 78 by means of a stud 79 and nut 80. The bracket 78 is mounted on the panel 45, and the stud 79 is parallel to the shaft 43. The rear portion of the shaft 71 is rotatably supported in a bearing 82 which is integral with an arm 83 projecting forwardly from one end of a sleeve 84 mounted on the stud 68. When the handwheel 74 is rotated, the shaft 56 will be rotated through the medium of the bevel gearing, and the nut 55 will travel to or from the shaft 43, thus changing the effective length of the arm 47. As the arm swings in response to movements of the regulator 31, the stud 68 will move in a circular are about the axis of shaft e3 as a center. At the .same time the shaft 71 will slide through the sleeve 76, and the sleeve will pivot on the bracket 78. The sleeve 84 will turn about the stud 68, and the pinion 75 will remain at all times in mesh with the gear. 67.

It is desirable to provide means whereby the operator may ascertain at aglance the position of adjustment of the nut 55 with respect to the shaft 56. For this purpose I have provided an indicator dial 86 having a revoluble pointer 67. The dial 86 is preferably mounted on the front of the panel 45, but for convenience in illustration it is shown in a plane at right angles thereto. The pointer 87 is connected by worm gearing 88 with one end of a flexible shaft or wire 99 mounted in a flexible tube 91. The other end of the wire 90 is fastened to a short shaft 92 which carries a bevel pinion 93 in mesh with the idler gear 67. The shaft 92 is rotatably supported in a bearing 95 formed integral with an arm 96 (Fig. 1) projecting upwardly from the sleeve 84. The flexible tube 91 is supported by a cap 97 mounted on the bearing 95. Markers 98 may be mounted on the dial 86 in positions which have been determined experimentally as correct for one, two, three, and four burners respectively.

The operation of the invention will now be apparent from the above disclosure. The regulator 31 controls rheostats 35 and the position of the arm 47 in accordance with the steam pressure. The rheostats determine the speed of the feeder motors 18 and hence the rate of fuel feed to the pulverizers 15 and to the burners 12. The air flow to the burners is controlled by the arm 47 through the rod 48, the lever 49 and the rod 52. If the number of burners in service is changed, the handwheel 74 will be rotated to bring the pointer 87 opposite to the proper marker 98. This will rotate the threaded shaft 56 and move the nut 55 to a new position, thus readjusting the damper 28 for the altered conditions. Since the arm 47 makes a greater angle with the rod 48 when the regulator is at the maximum load position than when it is at the minimum load position, adjustment of the effective length of the arm will cause a greater change in damper position under the former conditions than under the latter conditions. Hence the desired fuel-to-air ratio can be maintained at all ratings and with any number of burners in service. If the fuel-toair ratio tends to change at any time due to such factors as the characters of the fuel, for example, the operator need only turn the handwheel 74 slightly tocorrect the conditions. In many cases a carbon dioxide indicator Will be provided on the control panel 45 to assist the operator in obtaining efiicient combustion. The entire construction is simple and effective in operation, and comparatively inexpensive to manufacture and install.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. Regulating apparatus comprising a pivotally mounted arm, a screw-threaded shaft rotatably mounted on the arm, a nut mounted on the shaft, a bevel pinion fastened to one end of the shaft, an idler bevel gear in mesh with the pinion, a second bevel pinion in mesh with the idler gear, and a manually rotatable shaft connected to the second pinion, said parts being so arranged that the manually rotatable shaft may be utilized to rotate the screw-threaded shaft and cause the nut to travel along the latter shaft, thereby changing the effective length of the arm.

2. Regulating apparatus comprising a pivotally mounted arm, a screw-threaded shaft rotatably mounted on the arm, a nut mounted on the shaft and movable along the shaft to vary the efiective length of the arm as the shaft is rotated, a bevel pinion fastened to one end of the wait, an idler bevel gear in mesh with the pinion, a second bevel pinion in mesh with the idler gear, a manually rotatable shaft connected to the second pinion, a third bevel p-inion'in mesh with the idler gear, a flexible shaft connected to the third pinion, and an indicator actuated by the flexible shaft to indicate the position of the nut with respect to the screw-threaded shaft.

3. Regulating apparatus comprising a pivotally mounted arm, a screw-threaded shaft rotatably mounted on the arm, a nut mounted on the shaft and movable along the shaft to vary the efiective length of the arm as the shaft is rotated,

a bevel pinion fastened to one end of the shaft, an idler bevel gear in mesh with the pinion, a second bevel pinion in mesh with the idler gear, a manually rotatable shaft connected to the second pinion, a sleeve rotatably and slidably supporting the manually rotatable shaft, and a bracket pivotally supporting said sleeve.

4. Regulating apparatus comprising a pivotally mounted arm, a screw-threaded shaft rotatably mounted on the arm, a nut mounted on the shaft and movable along the shaft to vary the effective length of the arm as the shaft is rotated, a bevel pinion fastened to one end of the shaft, a stud mounted on the arm, an idler bevel gear rotatably supported on the stud and in mesh with the pinion, a second bevel pinion in mesh with the idler gear, a manually rotatable shaft connected to the second pinion, a sleeve rotatably supported on the stud, a bearing for the manually rotatable shaft, and an arm connecting the sleeve with the bearing.

5. Combustion regulating apparatus comprising an automatic regulator, a movable air flow control device, a connection between the regulator and the device, and a single manually adjustable member associated with said connection which may be adjusted to decrease the total movement of the air flow control device and at the same time decrease the minimum rate of air flow.

6. Combustion regulating apparatus comprising an automatic regulator, a movable air flow control device, a mechanical connection between the regulator and the device so arranged that the device will take a definite position for each position of the regulator within its range of movement, and a single manually adjustable member associated with said connection which, may be adjusted to decrease the total movement of the air flow control device and at the same time decrease the minimum rate of air flow.

7. Combustion regulating apparatus comprising a driving arm and a driven arm pivotally supported about parallel axes, means to move the driven arm through a fixed distance, a link connecting the arms, a movable air flow control device actuated by the driven arm, and means to adjust the link along one of the arms to vary the effective length of the arm, the parts being so constructed and arranged that adjustment of the said effective length to decrease the total move ment of the air flow control device will at the same time vary the end position of the device and decrease the minimum rate of air flow.

8. A combustion regulating system comprising a furnace, means to supply air thereto, a movable device to control the rate of air flow, an automatic regulator, two arms pivotally mounted about parallel axes, a link connecting the arms, means connecting the regulator to one of the arms to move the arm through a fixed distance, means connecting the other arm to the device, and means to adjust the link along one of the arms to vary the effective'length thereof, the parts being so constructed and arranged that adjustment of the said effective length to decrease the total movement of the device will at the same time vary the end position of the device and decrease the minimum rate of air flow.

PAUL C. TEMPLE. 

